I bought my 2012 F250 CC SB 6.2 back in December and really haven't had the truck in 4x4. Today we got a bit of snow. The roads were slippery so I engaged the 4x4 ESOF while at a stop sign (I know, didn't have to be stopped but I was so I put it in 4x4) The driveline was noticeably louder. I had a relatively constant hum that almost reminded me of a wheel bearing going bad. If you've ever experienced a wheel bearing going bad the sound gets louder as you go faster. I'm sure it's not a wheel bearing since it only makes the sound in 4x4. It's a fairly annoying sound and is louder than my old 99 F350. Anyone else notice the driveline being significantly louder in 4x4? There are no driving issues just a louder sound than what I was used to. I have the full Ford Certified warranty and can bring it in but I thought I'd run it by the brain trust here to get thoughts before going to the dealer.

 

My first thought would be to check the u-joints on both the front driveshaft and the front axle since they will all spin in 4x4, but not in 2wd. A u-joint with failing needle bearings will often make a whine for a little while before it completely locks up. It would also have the speed sensitive noise that you are describing.

 

I'll probably bring the truck in and let them give it a once over. It only has 35,000 miles on the odometer so I'd think that would be pretty premature even though it is a 5 year old truck. With the truck coming from Canada it probably spent a good bit of time in 4x4.
Thanks for the reply!

 

Also check the front diff fluid level. My mothers 2005 GMC 2500HD had a similar in 2008. You have to run 4x4 at least 10 miles once a year (according to GM) in order to keep the fluid and u-joints greased/lubed and in working order. Her truck she bought new and only has 41,000 miles on it. Your trucks previous owner probably haven't ran it that much in 4x4.

 

My brand new truck hums in 4x4. I have posted this topic in the 2017 section. I got a few responses that there previous gen SD's hummed also. Thing is, I've had about a dozen SD's in my life, and not one ever hummed like my new one. I can get it to go away when I'm coasting or let of the gas, but under any pedal pressure, it hums. It doesn't seem right to me.

 

My truck always has made a little more noise in 4WD. I consider that normal.

 

Mine does the exact same thing rain. No throttle, no noise. The sound almost reminds me of a loud throw out bearing in an old four speed, just not nearly as loud. If the radio is on at normal volume, I can't hear it.

 

Same here. I'm starting to wonder if I didn't hear my old truck because it had a 7.3 in it and you couldn't hear anything over the engine
Ron, It reminds me a lot of the sound of a wheel bearing going bad. I have a lot of experience with that problem from owning an Explorer.

 

My '12 doesn't make any extra noise in 4X4.

 

Mine gets loud in 4x4 but its just the noise of the transfer case and front driveline moving, which you don't hear in 2x4

 

The 01 has always hummed while in 4WD.

Even hubs locked in running down the highway it won't make any noise - and it would be spinning the u joints and front driveline and the transfer case bearings and chain would be spinning too.

Just one of those things.